Malignant mixed tumors of the major salivary glands.Special reference to the histologic structure in metastases

Abstract

In a suvery of 2211 tumors of the major salivary glands treated at Radiumhemmet and Karolinska Sjukhuset from 1921 to 1964 a preliminary reclassification resulted in 1633 being registered as mixed tumors, 34 of them as malignant. Material from metastases was available for histologic examination in 11 of these 34 cases. After a further study of the clinical course and careful histologic examination two were excluded—one in view of the lack of definite signs of malignancy and the other because the existence of another type of malignant tumor was more probable. In the remaining nine cases the primary tumor had the characteristics of a mixed tumor (pleomorphic adenoma), whereas only a carcinoma of varying type could be observed in the metastases. No pleomorphic structures were demonstrable in the metastases from any of the tumors of the salivary gland examined. On the basis of this study the authors question the existence of a tumor warranting the denotation of malignant mixed tumor. The term „cancer in pleomorphic adenoma”︁ is suggested as being more adequate for a tumor of this type.